In particulate material storage bins it is common practice to provide an auger system for unloading the bin. In U.S. Pat. No. 4,669,941 to West et al issued Jun. 2, 1987 is disclosed a bin sweeping auger for use in particulate material storage bins. A main auger extends form a center of the bin through one part of the wall for discharging the material from the center of the bin. A bin sweep auger is provided which carries out a sweeping movement about the bin floor from a position at one side of the main auger around an angle of just less than 360 degrees to a position on the other side of the main auger. At each position on either side of the main auger the bin sweep auger is parallel to the main auger and this movement is obtained by mounting the sweep auger on a double pivot arm arrangement where a first pivot point is provided at the center of the bin and a second pivot point at the outer end of a mounting arm is provided a short distance outwardly from the center.
This arrangement is commonly adopted and one difficulty in utilizing a system of this type is in providing drive to the bin sweep to carry it around the bin from one side position to the other.
Commonly the bin sweep is driven around the bin by a ground engaging wheel on an outside end of the sweep auger. The wheel is driven directly from the auger or in some cases is driven at reduced rotation rate, bearing in mind that the auger moves very slowly around the bin as it moves the material toward to center of the bin. Thus the rotational movement is very much slower than the rotation of the auger flight so the wheel is required to skid on the ground so that wear is applied to both the floor and the wheel. Also this drive system requires the use of friction which can of course fail to provide the necessary forwarding force in some cases so that the auger can become stuck.
Other systems of driving are known including positive drive elements arranged at the outer periphery of the bin. These do not work effectively in an arrangement which uses the double pivot connection since the position of the outside of the auger flight can vary relative to the outside of the bin.
In U.S. Pat. No. 5,318,444 (Kuzub et al) is shown in FIG. 8 an arrangement in which an outer end of the sweep auger is driven by a toothed wheel where the teeth engage onto the ground at the end of the auger flight. The toothed wheel is driven by an indexing arrangement so that each rotation of the auger flight rotates the toothed wheel through only a small increment significantly less than one rotation. In this way the toothed wheel is driven at a much slower rate than the auger flight to avoid rapid slippage of the toothed wheel on the floor which can cause significant wear and damage. However this arrangement has not achieved success and has not been adopted in other devices of this general type.
In U.S. Pat. Nos. 3,647,094 and 4,313,705 both of (Jackson) issued in 1972 and 1982 respectively is shown a complex multi-part auger carried on a series of ground wheels at spaced positions along the length of the multi-part auger. The auger is driven in its rotation around a central fixed point by hydraulic motors which are carried on the auger system and drive ground wheels through complex gear and chain arrangements. Again this arrangement has not been adopted in recent bin sweep arrangements.